Didemnum ascidian

Steglich s group coupled A-methyl bromoindolylmaleimide 36 with 5-tributylstannyl-l-methyl-1//-imidazole to afford 37 and then converted 37 to didemnimide C (38), an alkaloid isolated from the Caribbean ascidian Didemnum conchyliatum [25]. 5-Tributylstannyl- 1-methyl-IH-imidazole, in turn, was prepared according to Undheim s direct metalation method from 1-methyl- l/Z-imidazole [26]. 

Hyella caespitosa Bron et Flah Tedania ignis Nostoc sphaericum Tolypothrix tjipanasensis New Zealand Ascidian Australian Ascidian Didemnum sp. 

Eour years later, Kang and Eenical reported the isolation of ningalin D (282) from a marine ascidian of the genus Didemnum collected in Western Australia, near Ningaloo Reef. On the basis of the restricted rotation and also because of the apparent helicity, 282 could be chiral. However, from the marine source, it was available only in racemic form (248). 

Carroll, A.R. Bowden, B.F. Coll, J.C. Hockless, D.C.R. Skelton, B.W. White, A.H. (1994) Mollamide, a cytotoxic cyclic heptapeptide from the compound ascidian Didemnum molle. Aust. J. Chem., 47,61-69. 

Davis, R.A. Carroll, A.R. Pierens, G.K. Quinn, R.J. (1999A)New lamellarin alkaloids from the Australian ascidian, Didemnum chartaceum. J. Nat. Prod., 62, 419-24. 

Rudi, A. Aknin, M. Gaydou, E.M. Kashman, Y. (1998) Four new cytotoxic cyclic hexa- and heptapq>tides from the marine ascidian Didemnum molle. Tetrahedron, 54, 13203-10. 

Vervoort, H.C. Fenical, W. Keifer, P.A. (1999) A cyclized didemnimide alkaloid from the Caribbean ascidian Didemnum conchyliatum. J. Nat. Prod., 62,389-91. 

Lamellarin T-V and Y sulfates (67-70) were isolated from an unidentified ascidian from the Arabian Sea coast of India [97]. Four additional lamellarin sulfates, the 20-sulfates of lamellarins B, C and L and lamellarin G 8-sulfate (71-74) were isolated from Didemnum chartaceum from the Great Barrier Reef [98]. Unusually long relaxation times were observed for certain signals in the H NMR spectra of these compounds. Lamellarin a 20-sulfate (75) was isolated from an unidentified ascidian from India and was an inhibitor of human immunodeficiency virus type 1 (HIV-1) integrase [99]. 

Didemnolines A (31) and C (32) from the marine ascidian Didemnum sp. are cytotoxic to human epidermoid carcinoma KB cells (IC5o values of 6.1 and 0.28 pg/ml, respectively) and antimicrobial toward Staphylococcus aureus, Bacillus subtilis, and Escherichia coli [44,45]. 

Didemnimides B (219) and D (220) have been isolated from the Caribbean mangrove ascidian Didemnum conchyliatum [170]. 

Vervoort HC, Richards-Gross SE, Fenical W, Lee AY, Clardy J (1997) Didemnimides A-D Novel, Predator-Deterrent Alkaloids from the Caribbean Mangrove Ascidian Didemnum conchyliatum. J Org Chem 62 1486... 

Schumacher RW, Davidson BS (1995) Didemnolines A-D, New N9-Substituted P-Carbolines from the Marine Ascidian Didemnum sp. Tetrahedron 51 10125... 

Mitchell SS, Pomerantz SC, Concepcion GP, Ireland CM (1996) Tubercidin Analogs from the Ascidian Didemnum voeltzkowi. J Nat Prod 59 1000... 

Vervoort, H. C., Richards-Gross, S. E., Fenical, W., Lee, A. Y., and Clardy, J. C., Didemnimides A-D novel, predator-deterrent alkaloids from the Caribbean mangrove ascidian Didemnum conchyliatum, J. Org. Chem., 62, 1486, 1997. 

Lindquist, N. and Fenical, W., Ascidiatrienolides A-C, novel lactonized eicosanoids from the marine ascidian Didemnum candidum, Tetrahedron Lett., 30, 2735, 1989. 

Crude extracts of the ascidian Didemnum candidum exhibit strong inhibitory effects against phospholipase A2 in vitro. A search for the active component led to the discovery of ascidiatrienolide A 33 (20), an eicosatetraene derivative that is closely related to the didemnilactones 34-36 derived from the tunicate Didemnum moseley (27). The latter are endowed with high affinity to the leukotriene B4 receptor of human polymorphonuclear leucocyte membrane fractions. These fatty acid derivatives of marine origin provided yet another opportunity to validate our strategy for ( ,Z)-control outlined in the previous chapter based upon proper matching of the reactivity of the metathesis catalyst with the conformational preferences of a constrained substrate (22). 

Vervoort et al.115 next isolated and characterized a novel cyclized didemnimide alkaloid from the Caribbean Ascidian Didemnum conchyliatum. In prior work, the primary author and colleagues isolated and identified four novel alkaloids possessing unprecedented indole- maleimide imida/ole carbon frameworks, which ecological testing suggested served in a predator-deterrent role for the organism. Further fractionation led to a small quantity of a deep purple minor metabolite that required the use of micro-probe technology to facilitate its characterization. The molecule was shown to be related to the previously characterized molecules via cyclization to afford (52). 

Lamellarins were originally extracted from a marine prosobranch mollusk Lamdlaria sp. and subsequently from primitive chordate ascidians (tunicates) [23]. These ascidian species, knovm to produce many bioactive metabolites, likely represent the original producer of lamellarins because these organisms are presumed to be the dietary source of the Lamdlaria mollusks. Lamellarins have been isolated from different tunicates, including recently from the Indian ascidian Didemnum obscurum... 

Didemnaketal C (147) is an unusual heptaprenoid isolated from an ascidian Didemnum sp. its methanolysis product, didemnanaketal B (148), inhibited HIV-1 protease (12). 

Didmolamide A 379 and B 380 were isolated from the ascidian Didemnum molle collected from Madagascar <2003JNP575>. 

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